EP0261854B1 - Rack and pinion gear - Google Patents
Rack and pinion gear Download PDFInfo
- Publication number
- EP0261854B1 EP0261854B1 EP87308111A EP87308111A EP0261854B1 EP 0261854 B1 EP0261854 B1 EP 0261854B1 EP 87308111 A EP87308111 A EP 87308111A EP 87308111 A EP87308111 A EP 87308111A EP 0261854 B1 EP0261854 B1 EP 0261854B1
- Authority
- EP
- European Patent Office
- Prior art keywords
- rack
- pinion gear
- piston
- pinion
- bearing
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Lifetime
Links
Images
Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B62—LAND VEHICLES FOR TRAVELLING OTHERWISE THAN ON RAILS
- B62D—MOTOR VEHICLES; TRAILERS
- B62D5/00—Power-assisted or power-driven steering
- B62D5/06—Power-assisted or power-driven steering fluid, i.e. using a pressurised fluid for most or all the force required for steering a vehicle
- B62D5/20—Power-assisted or power-driven steering fluid, i.e. using a pressurised fluid for most or all the force required for steering a vehicle specially adapted for particular type of steering gear or particular application
- B62D5/22—Power-assisted or power-driven steering fluid, i.e. using a pressurised fluid for most or all the force required for steering a vehicle specially adapted for particular type of steering gear or particular application for rack-and-pinion type
Definitions
- the present invention relates to a rack and pinion gear particularly, but not exclusively, for a vehicle power assisted steering.
- the rack provides equal area piston faces to supporting bearings at its opposite ends disposed in a cylinder.
- the pinion is disposed substantially centrally with respect to the rack.
- Turning the steering causes pressure fluid to be preferentially diverted through a valve to the appropriate piston face as a result of which the rack is assisted in the appropriate direction.
- the provision of piston faces of equal area provides for equal power assistance on each lock.
- Unavoidable dimensional variations of the rack and cylinder, changing stiffness of the rack as it travels past the pinion and deflections caused by service loads, particularly the offset loading of the centre takeoff lead to inconsistent rack/pinion meshing.
- GB-A-813 312 discloses a rack and pinion gear comprising a rack which may be subject to the action of pressure fluid at either end and which is disposed in a cylinder, a pinion meshing with the rack and a first bearing for the rack adjacent to one end of the rack.
- GB-A-1 355 811 discloses a rack and pinion gear comprising a rack which may be subject to the action of pressure fluid at either end and which is disposed in a cylinder, a pinion meshing with the rack and a first bearing for the rack adjacent to one end of the rack.
- the rack and pinion gears described in both documents comprise a second bearing for the rack fixed to the cylinder at the position where the pinion and the rack mesh. This leads to three bearings in line, which is an unsatisfactory arrangement.
- a rack and pinion gear for a centre take off power assisted steering arrangement comprising a rack which may be subject to the action of pressure fluid on equal piston areas at either end and which is disposed in a cylinder, a pinion meshing with the rack, a first bearing for the rack adjacent to one end of the rack, and a second bearing for the rack fixed to the cylinder at the position where the pinion and rack mesh, characterised by the rack being disposed with clearance in a floating piston at its other end.
- the rack forms part of a centre take off power assisted steering arrangement for a vehicle.
- a seal is provided at the said one end of the rack and the floating piston also incorporates a seal.
- These seals each comprise a wiper seal, bearing ring and lip seal.
- the second bearing comprises a slipper which is urged against the rack by a compression spring.
- the spring is contained within a recess in the slipper and retained there by a plate fixed by bolts to the cylinder.
- the steering arrangement generally comprises a rack 1 and pinion 2.
- the rack 1 is supported in a surrounding cylinder 3 through bearings 4 and 5.
- Pressure fluid seals 6 and 7 are associated with respective ends of the rack.
- Pressure fluid inlets 8 and 9 lead into chambers disposed at opposite ends respectively of and partially defined by the rack 1 and cylinder 3. These inlets form part of a pressure fluid circuit which incorporates a valve which diverts pressure fluid to one end of the piston or the other depending upon the position of the steering. (Equivalent parts in Figures 1 and 2 bear the same reference numerals).
- Bearing 4 is conventional, but bearing 5 is not.
- Bearing 5 is shown in more detail in Figure 3. It comprises a plastics slipper 20, which is urged against the rack 1 by means of a compression spring 21. This spring 21 is accommodated in a recess in the slipper 20 and held there by a plate 22. The plate in turn is connected to the cylinder 3 by bolts 24 which extends through adjustment shims 23.
- This bearing 5 opposes the influence of stiffness, manufacturing tolerances and service loads on the rack at precisely the point where it is likely to cause the greatest problem, that is the point at which the pinion and rack mesh.
- the end of the rack 1 remote from the bearing 4 is provided with a floating piston arrangement.
- this comprises a piston 30 which surrounds the end of the rack 1 with clearance.
- the seal 7 comprises a wiper seal 31, bearing ring 32 and lip seal 33 which surround the piston 30.
- the piston 30 is connected to the rack 1 by means of a roll pin 34 which extends through holes in both the piston and rack. This connection is not necessary during normal operation as the piston is constantly urged against the end of the rack 1 by pressure fluid (oil). However, it is necessary for quality/testing purposes where the gear is stroked in an unpressurised condition in order to maintain a specified level of residual friction. To this end the piston/seal assembly must be retained with the rack.
- consis- tant meshing of pinion and rack is maintained and is not dependant on rack stiffness; manufacturing tolerances are compensated for and effects of service loads minimised.
Landscapes
- Engineering & Computer Science (AREA)
- Chemical & Material Sciences (AREA)
- Combustion & Propulsion (AREA)
- Transportation (AREA)
- Mechanical Engineering (AREA)
- Transmission Devices (AREA)
- Power Steering Mechanism (AREA)
Description
- The present invention relates to a rack and pinion gear particularly, but not exclusively, for a vehicle power assisted steering.
- In a known vehicle offtake power assisted steering arrangement, the rack provides equal area piston faces to supporting bearings at its opposite ends disposed in a cylinder. In the central position of the steering, the pinion is disposed substantially centrally with respect to the rack. Turning the steering causes pressure fluid to be preferentially diverted through a valve to the appropriate piston face as a result of which the rack is assisted in the appropriate direction. The provision of piston faces of equal area provides for equal power assistance on each lock. Unavoidable dimensional variations of the rack and cylinder, changing stiffness of the rack as it travels past the pinion and deflections caused by service loads, particularly the offset loading of the centre takeoff lead to inconsistent rack/pinion meshing. Two known rack and pinion gears which may provide for power assistance are disclosed in GB-A-813 312 and GB-A-1 355 811. Specifically, GB-A-813 812 discloses a rack and pinion gear comprising a rack which may be subject to the action of pressure fluid at either end and which is disposed in a cylinder, a pinion meshing with the rack and a first bearing for the rack adjacent to one end of the rack. A similar arrangement is disclosed in GB-A-1 355 811 and the rack and pinion gears described in both documents comprise a second bearing for the rack fixed to the cylinder at the position where the pinion and the rack mesh. This leads to three bearings in line, which is an unsatisfactory arrangement.
- According to the present invention, there is provided a rack and pinion gear for a centre take off power assisted steering arrangement comprising a rack which may be subject to the action of pressure fluid on equal piston areas at either end and which is disposed in a cylinder, a pinion meshing with the rack, a first bearing for the rack adjacent to one end of the rack, and a second bearing for the rack fixed to the cylinder at the position where the pinion and rack mesh, characterised by the rack being disposed with clearance in a floating piston at its other end.
- Use of a floating piston in conjunction with positioning of the second bearing at the pinion allows equal area pistons either end of a rack within a cylinder to be constrained radially at two positions only. In this way meshing of the rack and pinion is not dependent on rack stiffness, manufacturing tolerances are compensated for, and the effects of service loads are minimised.
- In a preferred embodiment of the invention, the rack forms part of a centre take off power assisted steering arrangement for a vehicle. A seal is provided at the said one end of the rack and the floating piston also incorporates a seal. These seals each comprise a wiper seal, bearing ring and lip seal. The second bearing comprises a slipper which is urged against the rack by a compression spring. The spring is contained within a recess in the slipper and retained there by a plate fixed by bolts to the cylinder. Although in normal operation the floating piston is urged against the adjacent end of the rack a connection between piston and rack is provided for testing purposes.
- In order that the invention may be more clearly understood, one embodiment thereof will now be described, by way of example, with reference to the accompanying drawings, in which:-
- Figure 1 shows a diagrammatic view of an existing centre take off power asssisted steering arrangement for a vehicle,
- Figure 2 shows a diagrammatic view of a centre take-off power assisted steering arrangement for a vehicle according to the present invention, and
- Figures 3 and 4 show detailed views of parts of the arrangement of Figure 2.
- Referring to Figure 2 of the drawings, the steering arrangement generally comprises a rack 1 and
pinion 2. The rack 1 is supported in a surrounding cylinder 3 throughbearings Pressure fluid seals 6 and 7 are associated with respective ends of the rack.Pressure fluid inlets -
Bearing 4 is conventional, but bearing 5 is not.Bearing 5 is shown in more detail in Figure 3. It comprises a plastics slipper 20, which is urged against the rack 1 by means of a compression spring 21. This spring 21 is accommodated in a recess in the slipper 20 and held there by a plate 22. The plate in turn is connected to the cylinder 3 by bolts 24 which extends through adjustment shims 23. This bearing 5 opposes the influence of stiffness, manufacturing tolerances and service loads on the rack at precisely the point where it is likely to cause the greatest problem, that is the point at which the pinion and rack mesh. - The end of the rack 1 remote from the
bearing 4 is provided with a floating piston arrangement. Referring to Figure 4, this comprises a piston 30 which surrounds the end of the rack 1 with clearance. Theseal 7 comprises a wiper seal 31, bearing ring 32 and lip seal 33 which surround the piston 30. The piston 30 is connected to the rack 1 by means of a roll pin 34 which extends through holes in both the piston and rack. This connection is not necessary during normal operation as the piston is constantly urged against the end of the rack 1 by pressure fluid (oil). However, it is necessary for quality/testing purposes where the gear is stroked in an unpressurised condition in order to maintain a specified level of residual friction. To this end the piston/seal assembly must be retained with the rack. - With the above described arrangement, consis- tant meshing of pinion and rack is maintained and is not dependant on rack stiffness; manufacturing tolerances are compensated for and effects of service loads minimised.
Claims (9)
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
GB8622691 | 1986-09-20 | ||
GB8622691A GB2196090B (en) | 1986-09-20 | 1986-09-20 | Rack and pinion gear |
Publications (2)
Publication Number | Publication Date |
---|---|
EP0261854A1 EP0261854A1 (en) | 1988-03-30 |
EP0261854B1 true EP0261854B1 (en) | 1991-01-09 |
Family
ID=10604515
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
EP87308111A Expired - Lifetime EP0261854B1 (en) | 1986-09-20 | 1987-09-15 | Rack and pinion gear |
Country Status (7)
Country | Link |
---|---|
US (1) | US4815552A (en) |
EP (1) | EP0261854B1 (en) |
JP (1) | JPS63101562A (en) |
AU (1) | AU583197B2 (en) |
DE (1) | DE3767258D1 (en) |
ES (1) | ES2020566B3 (en) |
GB (1) | GB2196090B (en) |
Families Citing this family (9)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JP3384105B2 (en) * | 1994-05-17 | 2003-03-10 | トヨタ自動車株式会社 | Rack and pinion type steering gear device |
DE19648737C1 (en) * | 1996-11-25 | 1998-04-02 | Daimler Benz Ag | Steering device with hydraulic coupling, in particular for a motor vehicle |
JPH1199953A (en) * | 1997-09-29 | 1999-04-13 | Trw Steering Systems Japan Co Ltd | Rack-and-pinion steering system |
US6098742A (en) | 1998-12-14 | 2000-08-08 | Trw Inc. | Steering apparatus |
JP4297575B2 (en) * | 1999-11-25 | 2009-07-15 | 株式会社ショーワ | Seal structure of tie rod mounting part in center take-off type power steering system |
US6457375B1 (en) * | 2000-07-25 | 2002-10-01 | Terry C. Buch | Rack and pinion assembly for use with steering mechanism of motor vehicles |
US7401677B2 (en) * | 2002-02-13 | 2008-07-22 | Trw Inc. | Self-centering steering system |
FR2857324B1 (en) * | 2003-07-08 | 2006-09-15 | Koyo Steering Europe Kse | BEARING FOR POWER STEERING HYDRAULIC OF MOTOR VEHICLE |
DE10336628A1 (en) * | 2003-08-05 | 2005-03-24 | Thyssenkrupp Presta Steertec Gmbh | Steering gear for a motor vehicle |
Family Cites Families (17)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
GB813312A (en) * | 1955-04-20 | 1959-05-13 | Hydrosteer Ltd | Improvements in steering mechanism |
US3061036A (en) * | 1959-07-23 | 1962-10-30 | Ford Motor Co | Power steering system |
GB1241428A (en) * | 1968-11-15 | 1971-08-04 | Adwest Eng Ltd | Rack and pinion steering mechanisms for motor vehicles |
GB1355811A (en) * | 1971-01-16 | 1974-06-05 | Burman & Sons Ltd | Vehicle steering gear |
DE2404077A1 (en) * | 1974-01-29 | 1975-08-07 | Audi Nsu Auto Union Ag | Hydraulically assisted rack and pinion steering - contains sealing element and piston connected to the rack and hydraulic line |
JPS524367A (en) * | 1975-06-27 | 1977-01-13 | Matsushita Electric Works Ltd | Dressing mirror |
JPS55119567A (en) * | 1979-03-03 | 1980-09-13 | Nissan Motor Co Ltd | Cylinder for rack type power steering |
JPS55119566A (en) * | 1979-03-03 | 1980-09-13 | Nissan Motor Co Ltd | Cylinder for rack type power steering |
DE2931184C2 (en) * | 1979-08-01 | 1984-01-12 | Zahnradfabrik Friedrichshafen Ag, 7990 Friedrichshafen | Rack and pinion power steering |
JPS5640069A (en) * | 1979-09-06 | 1981-04-16 | Nippon Steel Corp | Bottom construction of vertical furnace |
DE3118254C2 (en) * | 1981-05-08 | 1986-06-26 | Zahnradfabrik Friedrichshafen Ag, 7990 Friedrichshafen | Rack and pinion steering gear, in particular for motor vehicles |
JPS59140164A (en) * | 1983-01-31 | 1984-08-11 | Atsugi Motor Parts Co Ltd | Rack pinion system steering gear |
DE3463479D1 (en) * | 1983-03-22 | 1987-06-11 | Bendix Espana | Rack and pinion power steering, particularly with a central output |
ES527577A0 (en) * | 1983-11-18 | 1984-11-01 | Bendiberica Sa | AUTOMOBILE ASSISTED STEERING MECHANISM |
JPS6129517A (en) * | 1984-07-20 | 1986-02-10 | Kojima Press Co Ltd | Manufacture of regulator handle for vehicle |
GB8425632D0 (en) * | 1984-10-10 | 1984-11-14 | Adwest Eng Ltd | Rack and pinion steering mechanism |
JPS6210869A (en) * | 1985-07-08 | 1987-01-19 | Toshiba Corp | Fuel cell |
-
1986
- 1986-09-20 GB GB8622691A patent/GB2196090B/en not_active Expired - Fee Related
-
1987
- 1987-09-15 EP EP87308111A patent/EP0261854B1/en not_active Expired - Lifetime
- 1987-09-15 DE DE8787308111T patent/DE3767258D1/en not_active Expired - Fee Related
- 1987-09-15 ES ES87308111T patent/ES2020566B3/en not_active Expired - Lifetime
- 1987-09-17 US US07/097,821 patent/US4815552A/en not_active Expired - Fee Related
- 1987-09-18 JP JP62234693A patent/JPS63101562A/en active Pending
- 1987-09-18 AU AU78657/87A patent/AU583197B2/en not_active Ceased
Also Published As
Publication number | Publication date |
---|---|
JPS63101562A (en) | 1988-05-06 |
AU7865787A (en) | 1988-03-24 |
US4815552A (en) | 1989-03-28 |
ES2020566B3 (en) | 1991-08-16 |
EP0261854A1 (en) | 1988-03-30 |
GB8622691D0 (en) | 1986-10-29 |
GB2196090A (en) | 1988-04-20 |
GB2196090B (en) | 1990-05-16 |
DE3767258D1 (en) | 1991-02-14 |
AU583197B2 (en) | 1989-04-20 |
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